Field of the Invention
The present disclosure relates to a method of producing a positive electrode active material for a nonaqueous electrolyte secondary battery.
Description of Related Art
A positive electrode active material for a nonaqueous electrolyte secondary battery for application to large-sized power machines, such as electric vehicles, is required to have high output characteristics and high durability. In order to obtain high output characteristics, in a positive electrode active material having a structure in which a large number of primary particles are aggregated to form a secondary particles, it is effective, for example, to have a hollow structure in each secondary particle to increase the BET specific surface area, and to reduce the size of aggregated primary particles of each secondary particle. However, in such a positive electrode active material, one or more cracks may occur in the secondary particles due to pressurization in the formation of an electrode, expansion/shrinkage upon charge and discharge, etc., and there has been room for improvement in durability.
In relation to the above problems, a positive electrode active material containing lithium-transition metal oxide particles composed of a single particle or composed of a reduced number of primary particles forming each secondary particle and a method of producing the same are proposed, in which a lithium-transition metal composite oxide including aggregated secondary particles is ground to adjust the particle size of secondary particles, and the lithium-transition metal composite oxide after the particle size adjustment is subjected to another heat treatment (see, e.g., JP 2001-243949 A).